A gear box typically includes an input shaft and an output shaft in geared relationship with each other such that rotating speed of the input shaft and the rotating speed of the output shaft are different and defined by the geared relationship. The gear box may be used to drive a device operatively attached to the output shaft at the output rotating speed. A gear box having a single output shaft may be configured as a multiple speed gear box where the output speed of the gear box may be changed from a first rotating speed to a second rotation speed by disengaging and reengaging different combinations of gears in the gear box using a shift lever, selector fork, slidable coupling or clutch to disengage and engage different gears, or by changing out one or more gears from the gear box to change the gear ratio of the gear set connecting the input shaft to the output shaft. These methods for changing the output speed of the gear box require disengagement and reengagement of at least two gears in the gear box, where repeated disengagement and reengagement of gears may result in gear misalignment, wear, reduction of useful life, and/or noise in use.